Browse
Submit Data
Databases
API
Help

Dataset Information

36 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

N-heterocyclic carbene-catalyzed enantioselective Mannich reactions with alpha-aryloxyacetaldehydes.

ABSTRACT: N-Heterocyclic carbenes (NHCs) catalyze a new Mannich-type reaction to form beta-amino acid derivatives in high yield and enantioselectivity. The reaction is initiated by the addition of an NHC to an alpha-aryloxyaldehyde followed by elimination of a phenoxide anion which generates an enol/enolate. A Mannich addition to a tosylimine proceeds with excellent control over enantioselectivity. In a new carbene catalysis concept, catalyst regeneration is promoted by return, or rebound, and acylation of the phenoxide group which served as the activating component in the first step of the catalytic cycle. The activated ester products formed in situ are manipulated to form a variety of useful compounds including beta-amino acids, beta-amino amides, and peptides.

SUBMITTER: Kawanaka Y

PROVIDER: S-EPMC2836487 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

N-heterocyclic carbene-catalyzed enantioselective Mannich reactions with alpha-aryloxyacetaldehydes.

Kawanaka Yasufumi Y Phillips Eric M EM Scheidt Karl A KA

Journal of the American Chemical Society 20091201 50

N-Heterocyclic carbenes (NHCs) catalyze a new Mannich-type reaction to form beta-amino acid derivatives in high yield and enantioselectivity. The reaction is initiated by the addition of an NHC to an alpha-aryloxyaldehyde followed by elimination of a phenoxide anion which generates an enol/enolate. A Mannich addition to a tosylimine proceeds with excellent control over enantioselectivity. In a new carbene catalysis concept, catalyst regeneration is promoted by return, or rebound, and acylation o ...[more]

PMID: 20000857

Similar Datasets

Enantioselective N-heterocyclic carbene catalyzed annulation reactions with imidazolidinones.

Project description:Add acetic acid: A highly stereoselective N-heterocyclic carbene (NHC)-catalyzed formal [4+2] annulation between ?,?-unsaturated aldehydes and imidazolidinones for the synthesis of imidazoles has been developed. Acetic acid serves as a key additive to achieve high chemoselectivity for the formal [4+2]?annulation product.

| S-EPMC3905989 | biostudies-literature

A tandem dearomatization/rearomatization strategy: enantioselective N-heterocyclic carbene-catalyzed α-arylation.

Project description:In this study, the first example of the carbene-catalyzed tandem dearomatization/rearomatization reaction of azonaphthalenes with α-chloroaldehydes is described. This protocol enables the efficient assembly of chiral dihydrocinnolinone derivatives in good yields with excellent enantioselectivities (up to 99% ee). Moreover, this strategy enables not only the highly enantioselective NHC-catalyzed nucleophilic aromatic substitution, but also a formal Csp2-Csp3 bond formation.

| S-EPMC6385844 | biostudies-other

Chiral N-heterocyclic carbene-catalyzed generation of ester enolate equivalents from {alpha},{beta}-unsaturated aldehydes for enantioselective Diels-Alder reactions.

Project description:The catalytic generation of chiral ester enolate equivalents from ?,?-unsaturated aldehydes with chiral N-hetereocyclic carbene catalysts makes possible highly enantioselective hetero-Diels-Alder reactions. The reactions proceed under simple, mild conditions with both aliphatic and aromatic substituted enals as substrates. Previous attempts to employ these starting materials as enolate precursors gave structurally different products via catalytically generated homoenolate equivalents. Critical to the success of the enolate generation was the strength of the catalytic base used to generate the active N-heterocyclic carbene catalyst. To complement these studies, we have investigated the enolate structure using computational methods and find that it prefers conformations perpendicular to the triazolium core.

| S-EPMC2996418 | biostudies-other

α,β-Unsaturated acyl azoliums from N-heterocyclic carbene catalyzed reactions: observation and mechanistic investigation.

Project description: Not available

| S-EPMC3189509 | biostudies-literature

Enantioselective <i>N</i>-heterocyclic carbene-catalyzed nucleophilic dearomatization of alkyl pyridiniums.

Project description:NHC-catalyzed nucleophilic dearomatization of alkyl pyridiniums has been achieved to generate 1,4-dihydropyridines with high enantioselectivity. This is a rare example of catalytic, asymmetric addition of a nucleophile to the activated pyridinium that prefers C-4 functionalization leading to the 1,4-dihydropyridine with high selectivity.

| S-EPMC5627355 | biostudies-literature

Alpha'-hydroxyenones as mechanistic probes and scope-expanding surrogates for alpha,beta-unsaturated aldehydes in N-heterocyclic carbene-catalyzed reactions.

Project description:N-heterocyclic carbene-catalyzed reactions of alpha,beta-unsaturated aldehydes and a variety of electrophiles allow the facile preparation of a diverse array of annulation products including trisubstituted cyclopentenes, gamma-lactams, and bicyclic beta-lactams. The substrate scope of these reactions, however, is limited by the difficulties of preparing the starting alpha,beta-unsaturated aldehydes. We now report that alpha'-hydroxyenones, which can be prepared in a single convenient step from aromatic and heteroaromatic aldehydes, can serve as efficient surrogates for enals in the annulation reactions. This protocol allows the facile preparation and use of substrates bearing nitrogen heterocycles. These reagents have also allowed us to demonstrate that, in contrast to other classes of aldehydes, the formation of the Breslow intermediate from enals and N-heterocyclic carbenes is irreversible under the reaction conditions.

| S-EPMC2907655 | biostudies-literature

N-Heterocyclic Carbene Catalyzed Enantioselective Annulation of Benzothiazolyl Ethyl Acetates with 2-Bromoenals.

Project description:An N-heterocyclic carbene catalyzed enantioselective [3+3] annulation of benzothiazolyl acetates with 2-bromoenals has been developed. The protocol provides a direct asymmetric synthesis of dihydro-1H-benzothiazolopyridinones in good to very good yields and medium ee values. In many cases, the virtually enantiopure heterocycles are available through a single recrystallization (99% ee).

| S-EPMC4702349 | biostudies-literature

Cyclopropenimine-catalyzed enantioselective Mannich reactions of tert-butyl glycinates with N-Boc-imines.

Project description:Cyclopropenimine 1 is shown to catalyze Mannich reactions between glycine imines and N-Boc-aldimines with high levels of enantio- and diastereocontrol. The reactivity of 1 is shown to be substantially greater than that of a widely used thiourea cinchona alkaloid-derived catalyst. A variety of aryl and aliphatic N-Boc-aldimines are effective substrates for this transformation. A preparative-scale reaction to deliver >90 mmol of product is shown using 1 mol % catalyst. The products of this transformation can be converted into several useful derivatives.

| S-EPMC3804837 | biostudies-literature

Gold(I)-catalyzed diastereo- and enantioselective 1,3-dipolar cycloaddition and Mannich reactions of azlactones.

Project description:Azlactones participate in stereoselective reactions with electron-deficient alkenes and N-sulfonyl aldimines to give products of 1,3-dipolar cycloaddition and Mannich addition reactions, respectively. Both of these reactions proceed with good to excellent diastereo- and enantioselectivity using a single class of gold catalysts, namely C(2)-symmetric bis(phosphinegold(I) carboxylate) complexes. The development of the azlactone Mannich reaction to provide fully protected anti-?,?-diamino acid derivatives is described. 1,3-Dipolar cycloaddition reactions of several acyclic 1,2-disubstituted alkenes and the chemistry of the resultant cycloadducts are examined to probe the stereochemical course of this reaction. Reaction kinetics and tandem mass spectrometry studies of both the cycloaddition and Mannich reactions are reported. These studies support a mechanism in which the gold complexes catalyze addition reactions through nucleophile activation rather than the more typical activation of the electrophilic reaction component.

| S-EPMC3056178 | biostudies-literature

Highly enantioselective three-component direct Mannich reactions of unfunctionalized ketones catalyzed by bifunctional organocatalysts.

Project description:A highly stereoselective three-component direct Mannich reaction between aromatic aldehydes, p-toluenesulfonamide, and unfunctionalized ketones was achieved through an enolate mechanism for the first time with a bifunctional quinidine thiourea catalyst. The corresponding N-tosylated β-aminoketones were obtained in high yields and excellent diastereo- and enantioselectivities (up to >99:1 dr and >99% ee).

| S-EPMC3575191 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data